Southern Ragweed
Ambrosia bidentata
Last reviewed: June 2026
Light
full sun
Water
low
Size
12"–48" H × 6"–24" W
Bloom
Jul, Aug, Sep
Native to
AL, AR, CT, GA and 20 more states
Pollinators
bees, beetles, flies
Browse plants for this ecoregion
Southern ragweed is an annual wildflower that grows 1-4 feet tall with small, inconspicuous greenish flowers from summer through early fall. This native plant thrives in full sun and drought conditions, making it well-suited to low-maintenance naturalized areas. It produces abundant pollen and seeds that support wildlife through the growing season.
In an HOA neighborhood
Southern Ragweed takes more care to keep looking intentional in a front yard. Maintenance level: low. Consider it for backyard or mid-zone beds rather than the street edge.
Works well in: backyard only.
- Widely considered a weed by homeowners
- Produces allergenic pollen
- Informal appearance conflicts with maintained landscape expectations
Wildlife value
Host plant for red-banded hairstreak.
The flowers attract bees, beetles, and flies during summer blooming. Seeds provide food for birds, particularly finches and sparrows in fall.
Common questions
- How much sun does Southern Ragweed need?
- Southern Ragweed grows best in full sun conditions.
- When does Southern Ragweed bloom?
- Southern Ragweed blooms in July, August, and September.
- Where is Southern Ragweed native?
- Southern Ragweed (Ambrosia bidentata) is native to AL, AR, CT, GA and 20 more states, per the USDA PLANTS Database and regional native plant society lists.
- What butterflies or moths does Southern Ragweed host?
- Southern Ragweed is a larval host plant for red-banded hairstreak.
- Is Southern Ragweed HOA-friendly?
- Southern Ragweed takes more care to look intentional in a front yard. Consider it for backyard or mid-zone beds rather than the street edge.
Native range data from the USDA PLANTS Database and regional native plant society lists. Pollinator and host plant associations compiled from GBIF, iNaturalist, and published ecological literature.
Ready to grow Southern Ragweed? Add it to your garden in Pollinator Patch to track it and get season-by-season care guidance.